In medical imaging, picture archiving and communication systems (PACS) are a combination of computers and/or networks dedicated to the storage, retrieval, presentation and distribution of images. While images may be stored in a variety of formats, the most common format for image storage is Digital Imaging and Communications in Medicine (DICOM). DICOM is a standard in which radiographic images and associated meta-data are communicated to the PACS system from imaging modalities for interaction by end-user medical personnel.
PACS display textual and graphical medical information that are associated with image attributes. Some of this information is received from DICOM and some is generated within the PACS as annotations that are associated with the images or measurements linked to anatomical regions of interest or markers that are produced by third party systems, such as Computer Aided Detection (CAD) applications. The DICOM standard recently introduced support for Structured Reports (SR) that can include CAD findings and GSPS (Grayscale SoftCopy Presentation State) non-image objects that are necessary to reproduce the same visualization of an image if displayed at two disparate PACS systems. Not all annotations are covered under the GSPS umbrella and often these attributes are displayed as static image overlays that can be turned on or off, based on the viewer's preference.
For example, certain attributes that are related to image processing are displayed as alphanumeric annotations that are associated with the rendering of a particular image. The use of an image as a diagnostic or analytical tool generally requires that images be labeled by appropriate medical personnel. The labeling of images is accomplished by the annotation of points or regions, on a displayed image, with a descriptor such as a label. The descriptor may be user provided such as manually typed text/numbers or be predefined alphanumeric strings that are selectable by the user. All users are thus able to identify image regions as a result of these labels.
Since an object or body part of interest will typically have multiple images taken or generated from different perspectives or views (i.e. sagittal, transverse, orthogonal, curved MPR, etc.), it would be beneficial for the labels to appear on the various views of the image irrespective of the view that is being displayed. The labels thus provide a reference point between the displayed images. More importantly, it would be beneficial for the label of a particular region to be propagated to all views and all images of that region within a given system.
For example, in the area of spine labeling, text annotations are provided in proximity to vertebral and inter-vetebral regions of an image of a spine, to serve as points of reference for any user viewing the image. In the imaging process for the spine, a first image may obtained in the sagittal plane, a second image or series of images may be obtained in the orthogonal plane and a third series of other images may be taken in the axial plane. The label for any particular vertebrae in the first image is also required on the second and third series of images. Traditionally, this labeling process is manual in nature. That is, a user with the aid of a mouse or other pointing device locates a vertebra in the first image, and then locates other instances of that vertebra in the second and third series of images. This annotation process is very time consuming. Furthermore, this process is prone to errors as the labels must be consistently placed in each of the images within each of the series of images.
To overcome some of the deficiencies described above, some systems have attempted to minimize the amount of manual effort that may be required to propagate spine labels between the different images and views. However, these systems suffer from drawbacks of their own. These solutions utilize a single point label in one view of an image to propagate that label to an orthogonal view of the image, such as by finding the single point of intersection of the orthogonal plane and the label point. One of many disadvantages and draw backs to this method is the fact that such a system would not allow a continuous display of labels as a user moves through the various slices of an orthogonal view since only the single slice that intersects the point on the sagittal view would have a label. Another disadvantage lies in the issue of accuracy in of the labeling of an orthogonal or axial slice. Since the plane of the axial slice may not exactly intersect the labeled point on the sagittal view, some approximation of the proximity of the axial slice to the intersection point is required. This aspect would not only introduce errors in labeling, but may also confuse or mislead a user who may be expecting a label as a certain axial image view is displayed.
What is needed is an intuitive and quick method for labeling images that transcends the problems highlighted above and provides a simplified yet efficient and reliable identification of image regions irrespective of the view that is displayed. In other words, a system that avoids the tedium of manual labeling, propagates labels to the various views and various related images in a series. The present invention fills these needs as well as other needs.